Evaluation of glucose tolerance in methimazole and Radioiodine treated Graves’ patients

Background: One of the major concerns of the administration of radioiodine is its complications. The pancreas has sodium iodine symporter and may concentrate radioiodine. Objectives: This study compared glucose tolerance in Graves’ disease patients on continuous treatment with methimazole to radioiodine-treated hypothyroid patients on levothyroxine. Materials and Methods: In this study 132 patients with Graves’ disease who had relapsed after drug therapy were studied. Fifty-nine were on long term treatment with methimazole, and 73 were radioiodine treated hypothyroid patients on levothyroxine. In each group the glucose tolerance test was performed, and serum lipid profiles and glucose, TSH, insulin concentrations, and HOMA-IR and HOMA-B values were measured. Results: No significant differences were observed in age, sex, BMI, and BP between the two groups. Mean FBS and HOMA-IR in the radioactive iodine group were higher than in the methimazole group: 94 mg/dl versus 90 mg/dl, P = 0.019 and 1.5 (1.2-2.3) versus1.3 (0.8-2.1), P = 0.045, respectively. After controlling for family history of diabetes and total cholesterol, the two groups were not significantly different on any of the dependent variables. No significant differences were found between the two groups on the HOMA-B, median 2-hour blood glucose, and serum-insulin levels. Conclusions: The results of this study indicate that radioiodine treatment had no adverse effects on glucose tolerance and insulin resistance.